ENGINE STALLS

I have a Nissan ALTIMA 2006 SL, I am having problems with the engine It stalls every week. When you put it on Neutral or Parking the car does not accelerate. But when I turn off the car then turn it on it starts working again but the Service Engine Soon light is still on. I went to the garage and had it scan with a scanner BOSCH KTS 200, the first time it triggered this message:
Pedal acceleration synchronization error. After the scan the signal dissapeared. This week I had the same problem I had it scan again but now it triggered another error: P2138: Unknown error.
I had the Airbag scanned too it triggered 3 errors:
- Front ABS sensor was triggered
- Front impact sensor communication fault
- Driver side front airbag igniter circuit - Open Circuit
How to fix this accelaration problem and Airbag if possible?
Thank You

The Throttle bore has not been touched, I went to check it at the auto service. The guy told me I have to change the whole accelerator system which includes the throttle position sensor. Do I really have to change the whole system or just the throttle position sensor?
What about the problems with the Airbag system?
Regards

"HARNESS CONNECTOR DAMAGE IS COMMON AFTER DEPLOYMENT. In particular, the push in locking device (usually black) gets damaged if not released before removing the connector from the bag. Driver side common melting problems requiring clockspring replacement. The locking device also serves to release the airbag shorting bars so, if they are damaged or missing, you will get a "short circuit" code. Try with 2ohm - 1/4 watt resistors in the harness side and clear codes."

For diagnosis, this is where we start:
Turn the ignition key on and foolow the air bag light for the following patterns and get back to me:

HI,
I ran the VIN, and found out the car was involved in car accident in 07/2007 and the air bag was deployed, that s why I think it s not working now.
I have problems reading the attachment of the Airbag system and the three first indications are missing.
The car was not part of any recalls too.